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    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* 和三角形基本一致，多一个圆角的样式 */
        div {
            width: 0;
            height: 0;
            border: 50px solid transparent;
            border-top-color: red;
            border-radius: 100px;
        }
    </style>
</head>

<body>
    <h1>实现一个扇形</h1>
    <div></div>
</body>

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